Hemp Hurds as Paper-Making Material

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Hemp Hurds as Paper-Making Material, by

Lyster H. Dewey and Jason L. Merrill This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org
Title: Hemp Hurds as Paper-Making Material United States Department of Agriculture, Bulletin No. 404
Author: Lyster H. Dewey and Jason L. Merrill
Release Date: February 25, 2006 [EBook #17855]
Language: English
Character set encoding: ISO-8859-1
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UNITED STATES DEPARTMENT OF AGRICULTURE
=BULLETIN No. 404=
Contribution from the Bureau of Plant Industry WM. A. TAYLOR, Chief
[Illustration: USDA crests flanking bulletin banner]
Washington, D.C. PROFESSIONAL PAPER October 14, 1916
HEMP HURDS AS PAPER-MAKING MATERIAL.
By LYSTER H. DEWEY, Botanist in Charge of Fiber-Plant Investigations, and JASON L. MERRILL, Paper-Plant Chemist, Paper-Plant Investigations.
=CONTENTS.= Page. The production and handling of hemp hurds, by Lyster H. Dewey:
What hemp hurds are 1 Pith, wood, and fiber 2 Character of hurds affected by retting 2 Proportion of hurds to fiber and yield per acre 3 Hurds available from machine-broken hemp 3 Present uses of hemp hurds 4 Present supplies of hurds available 5 Baling for shipment 5 Cost of baling 5 Summary 6
The manufacture of paper from hemp hurds, by Jason L. Merrill:
Introduction 7 Factors justifying an investigation of hemp hurds 8 Character of the material 11 Character of the tests 12 Operations involved in a test 13 Description of tests 16 Comparison of the tests and commercial practice 21 Physical tests of the papers produced 24 Conclusions 25
In preparing the report on the manufacture of paper from hemp hurds it became evident that a short discussion of the agricultural aspects of this material should be included in the publication. Such an article was prepared, therefore, and the two reports are here presented together.
[NOTE.--This bulletin should be useful to all persons who are interested in the economic phases of paper making, especially to print and book paper manufacturers. It also should be of interest to scientific investigators and chemists.]

=THE PRODUCTION AND HANDLING OF HEMP HURDS.=
By LYSTER H. DEWEY, Botanist in Charge of Fiber-Plant Investigations.
=WHAT HEMP HURDS ARE.=
The woody inner portion of the hemp stalk, broken into pieces and separated from the fiber in the processes of breaking and scutching, is called hemp hurds. These hurds correspond to shives in flax, but are much coarser and are usually softer in texture.
The hemp stalk grown in a broadcast crop for fiber production is from one-eighth to three-eighths of an inch in diameter and from 4 to 10 feet tall. The stalk is hollow, with a cylindrical woody shell, thick near the base, where the stalk is nearly solid, and thinner above, where the hollow is relatively wider.
In the process of breaking, the woody cylinder inside of the fiber-bearing bark is broken into pieces one-half of an inch to 3 inches long and usually split into numerous segments. The thicker lower sections are split less than the thin-shelled upper ones, and they are often left quite solid.
=PITH, WOOD, AND FIBER.=
The inner surface of the hurds usually bears a layer of pith, consisting of thin-walled cells nearly spherical or angular, but not elongated. They are more or less crushed and torn. They are probably of little value for paper, but they constitute less than 1 per cent of the weight of the hurds. The principal weight and bulk consist of slender elongated woody cells. The outer surface is covered with fine secondary fibers composed of slender elongated cells, tougher than those of the wood but finer and shorter than those of the hemp fiber of commerce. No method has been devised thus far which completely separates from the hurds all of the long fiber. From 5 to 15 per cent of the weight of the hurds consists of hemp fiber, in strands from 3 inches to 8 feet in length. Some fragments of the bark, made up of short cubical cells, usually dark in color, cling to the strands of fiber.
=CHARACTER OF HURDS AFFECTED BY RETTING.=
Nearly all of the hemp in the United States is dew retted. The stalks are spread on the ground in swaths as grain is laid by the cradle. The action of the weather, dew, and rain, aided by bacteria, dissolves and washes out the green coloring matter (chlorophyll) and most of the gums, leaving only the fibrous bark and the wood. The plants in this process lose about 60 per cent of their green weight, or about 40 per cent of their air-dry weight.
The stalks are sometimes set up in shocks to cure before retting, and after retting they are set up in shocks to dry. Each time the stalks